Researchers said elephants can tell the difference between human languages, and they can tell whether a voice comes from a man, woman or boy.

The study was conducted at Amboseli National Park, in Kenya, where hundreds of wild elephants live among humans.

Researchers recorded the voices of Maasai men, who on occasion kill elephants in confrontations over grazing for cattle, and Kamba men, who are less of a threat to the elephants. The recordings contained the same phrase: "Look over there. A group of elephants is coming," in two different languages.

Still other recordings were made of female Maasai speakers and young Maasai boys. When the recordings were played for hundreds of elephants across 47 family groups, the reactions were startling.

When elephants heard the adult male Maasai voices, they tended to bunch together or move cautiously away. But when the elephants heard Maasai females, boys, or adult male Kamba speakers, they did not show concern.

The study was released Monday in the Proceedings of the National Academy of Sciences.